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Video Solution: Each of the following species will be encountered at some po...

Problem

Each of the following species will be encountered at some point in this text. They all have the same number of electrons binding the same number of atoms and the same arrangement of bonds; they are isoelectronic. Specify which atoms, if any, bear a formal charge in the Lewis structure given and the net charge for each species. 

(a) :N≡N:

Video Transcript

Hey guys my name is Jonathan and today we're going to go ahead and figure out our formal charges for these molecules. Remember, we've got two different ways, right? we can use our standard group number, minus sticks plus dots, right? Forgive my bad handwriting or we could just look at our bonding preference that Johnny asked us to memorize, right? So, for a couple of these, we're just going to go ahead and look at our group number of minus sticks plus dots, so what's the group number of nitrogen? nitrogen is in group number five, right? So, 5 minus and now we look at this? Well, how many sticks does this have connected to it? 3 how many dots? two, so we do this, 5 minus 5 right? this is equal to 0, so this nitrogen has a formal charge of 0. So, no charge, that's good, this next one is exactly the same thing, right? It's got three bonds. So, three sticks and two dots, so it's got a zero formal charge. Now, what about this next carbon? carbon guys is in group number four, right? And it's got three, three sticks and two dots, right? So, four minus 5 that's going to give us a negative 1 charge, so this carbon has a negative charge, this nitrogen because it's the same thing is these two appear, right? Three sticks and two dots it's going to have a zero formal charge, so the net charge on this molecule a is negative one. Now, this next one guys now we're going to use our bonding preference. Carbon likes to have four bonds, right? But here, it's got three bonds and a lone pair, so we know it's going to have a negative charge and just in case we can go ahead and do this again, right? We've got group number 4, right? minus 3 sticks plus 2 dots in parenthesis just like up here, so we know that this has a negative 1 charge, this carbon over here is also in the same exact arrangement, so it's going to have a negative charge as well, giving this whole molecule a net charge of negative 2. Now, what about this one over here? well, we look, we see that nitrogen is in group number 5, right? It's got 2 dots, 3 sticks, right? So it's got a zero formal charge and we know that nitrogen likes to have three bonds and a lone pair before it's bonding preference, oxygen likes to have two bonds and two lone pairs, right? For its zero charge but here it's got three bonds and one lone pair and I can tell you right now this has a positive charge just because I memorized my bonding preferences, but let's go ahead and do this properly with our group number. So, group number of oxygen is 6 minus 3, right? 3 sticks plus 2 dots. So, 6 minus 5 that's going to equal positive 1. Now, this next one over here, we've got, and guys what's the net charge on this? it's a positive charge, right? So, down here we know this carbon just like over here it's going to have a negative charge and now this oxygen just like this guy up here it's going to have a positive charge, right? Negative charge, positive charge. So, our net charge on the form on the entire molecule is going to be zero, right? So guys, if you have any questions please feel free to ask me, if not, let's move on.